Can confirm that this is happening once one is trying to add a cluster member from the alive unit, which isn't the leader: $ juju status mysql-innodb-cluster Model Controller Cloud/Region Version SLA Timestamp openstack foundations-maas maas_cloud 2.9.42 unsupported 07:39:54Z App Version Status Scale Charm Channel Rev Exposed Message logrotated active 3 logrotated stable 10 no Unit is ready. mysql-innodb-cluster 8.0.32 blocked 3 mysql-innodb-cluster 8.0/stable 43 no Cluster is inaccessible from this instance. Please check logs for details. Unit Workload Agent Machine Public address Ports Message mysql-innodb-cluster/0 blocked idle 5/lxd/2 172.27.85.230 Cluster is inaccessible from this instance. Please check logs for details. logrotated/26 active idle 172.27.85.230 Unit is ready. mysql-innodb-cluster/1 blocked idle 6/lxd/1 172.27.85.249 Cluster is inaccessible from this instance. Please check logs for details. logrotated/25 active idle 172.27.85.249 Unit is ready. mysql-innodb-cluster/2* blocked executing 7/lxd/2 172.27.85.237 Cluster is inaccessible from this instance. Please check logs for details. logrotated/23 active executing 172.27.85.237 Unit is ready. Machine State Address Inst id Series AZ Message 5 started 172.27.85.222 node06 focal default Deployed 5/lxd/2 started 172.27.85.230 juju-2f3dae-5-lxd-2 focal default Container started 6 started 172.27.85.223 node07 focal default Deployed 6/lxd/1 started 172.27.85.249 juju-2f3dae-6-lxd-1 focal default Container started 7 started 172.27.85.225 node08 focal default Deployed 7/lxd/2 started 172.27.85.237 juju-2f3dae-7-lxd-2 focal default Container started 130 ubuntu@orangebox84:~$ juju run-action mysql-innodb-cluster/0 add-instance address=172.27.84.111 --wait unit-mysql-innodb-cluster-0: UnitId: mysql-innodb-cluster/0 id: "90" message: exit status 1 results: ReturnCode: 1 Stderr: | ERROR cannot write leadership settings: cannot write settings: not the leader Traceback (most recent call last): File "/var/lib/juju/agents/unit-mysql-innodb-cluster-0/charm/actions/add-instance", line 265, in add_instance output = instance.configure_and_add_instance(address) File "/var/lib/juju/agents/unit-mysql-innodb-cluster-0/charm/lib/charm/openstack/mysql_innodb_cluster.py", line 1091, in configure_and_add_instance self.configure_instance(address) File "/var/lib/juju/agents/unit-mysql-innodb-cluster-0/charm/lib/charm/openstack/mysql_innodb_cluster.py", line 614, in configure_instance leadership.leader_set({ File "/var/lib/juju/agents/unit-mysql-innodb-cluster-0/.venv/lib/python3.8/site-packages/charms/reactive/decorators.py", line 219, in _wrapped return func(*args, **kwargs) File "/var/lib/juju/agents/unit-mysql-innodb-cluster-0/charm/lib/charms/leadership.py", line 62, in leader_set hookenv.leader_set(settings) File "/var/lib/juju/agents/unit-mysql-innodb-cluster-0/.venv/lib/python3.8/site-packages/charmhelpers/core/hookenv.py", line 1180, in inner_translate_exc2 return f(*args, **kwargs) File "/var/lib/juju/agents/unit-mysql-innodb-cluster-0/.venv/lib/python3.8/site-packages/charmhelpers/core/hookenv.py", line 1241, in leader_set subprocess.check_call(cmd) File "/usr/lib/python3.8/subprocess.py", line 364, in check_call raise CalledProcessError(retcode, cmd) subprocess.CalledProcessError: Command '['leader-set', 'cluster-instance-configured-172-27-84-111=True']' returned non-zero exit status 1. During handling of the above exception, another exception occurred: Traceback (most recent call last): File "/var/lib/juju/agents/unit-mysql-innodb-cluster-0/charm/actions/add-instance", line 379, in main action(args) File "/var/lib/juju/agents/unit-mysql-innodb-cluster-0/charm/actions/add-instance", line 272, in add_instance "output": e.stderr.decode("UTF-8"), AttributeError: 'NoneType' object has no attribute 'decode' During handling of the above exception, another exception occurred: Traceback (most recent call last): File "/var/lib/juju/agents/unit-mysql-innodb-cluster-0/charm/actions/add-instance", line 391, in sys.exit(main(sys.argv)) File "/var/lib/juju/agents/unit-mysql-innodb-cluster-0/charm/actions/add-instance", line 382, in main "output": e.output.decode("UTF-8"), AttributeError: 'AttributeError' object has no attribute 'output' status: failed timing: completed: 2023-04-19 09:32:56 +0000 UTC enqueued: 2023-04-19 09:32:25 +0000 UTC started: 2023-04-19 09:32:26 +0000 UTC